High-efficiency sub-watt in-band-pumped single-frequency DBR Tm³⁺-doped germanate fiber laser at 1950 nm

Abstract

Based on a 1.8-cm-long heavily Tm-doped germanate fiber and being in-band-pumped by a 1610 nm single-mode laser, a high-efficiency and high-power single-frequency distribute Bragg reflector (DBR) fiber laser emitting at 1950 nm is demonstrated. The DBR fiber laser has a maximum output power of ~617 mW and a slope efficiency for the absorbed pump power reaches to more than 42.2%. A stable single-longitudinal-mode laser output with a signal-to-noise ratio of greater than 63 dB is realized. The measured relative intensity-noise of the fiber laser reaches to around -150 dB/Hz at frequencies of over 8.4 MHz. It is beneficial to exploit the sub-watt and high-efficiency single-frequency laser from fiber oscillators directly, especially in the application of multiple paths coherent beam combination and optical medical technology.

Recent progress of high-power single-frequency all-fiber oscillators and amplifiers

“…The maximum output power of 617 mW was achieved with a slope efficiency of 42.2%. The output signal-to-noise ratio was up to 63 dB and the 3-dB linewidth was 12.55 kHz [20]. Ring cavity has also been developed for high-power single-frequency fiber laser demonstration.…”

Single-frequency fiber lasers based on metal thiophosphites with sub-kHz linewidths

“…After decades of research, SFFLs have found a variety of uses in optical sensing, optical measurement, and coherent optical communication. [1][2][3][4][5] The most commonly used configurations for SFFLs include the construction of distributed feedback (DFB) fiber lasers, [6][7][8] distributed Bragg reflector (DBR) fiber lasers, [9][10][11][12][13][14] and ring-cavity fiber lasers with ultranarrow-bandwidth filters. [15][16][17] However, the DBR and DFB fiber lasers cannot efficiently absorb the pump power and also need accurate and costly fiber Bragg gratings (FBGs), whilst the ring-cavity fiber lasers have a complex and unstable structure.…”

2.56 W Single‐Frequency All‐Fiber Oscillator at 1720 nm

“…In the past decade, based on heavily rare earth‐doped, multicomponent oxide glass fibers, single‐frequency output power of short‐cavity fiber lasers has reached the level of hundreds of milliwatts with wavelengths in the 1, 1.5, and 2 μm regime. [ 12–14 ] However, issues such as spatial hole burning and gain saturation still limit the power scaling of these short‐cavity lasers. Polynkin et al reported a single‐frequency, short‐cavity oscillator at 1.5 μm using a twisted‐mode cavity to eliminate spatial hole burning and achieved an output power of 1.9 W. [ 15 ] Following this work, the same group used a 3.8 cm‐long photonic crystal, phosphate glass fiber with a highly erbium‐doped large‐area core to avoid gain saturation.…”